Characterization of microclimate in mist and non-mist propagation systems

Publisher Website
Google Scholar
Abstract
The microclimates of two contrasting propagation systems, a polyethylene-covered mist unit and a low-technology, non-mist polyethylene propagator, were examined in detail over a two year period. Both systems were able to maintain relative humidities (r.h.) of over 90% for much of the time; r.h. below 60% was associated with peaks in irradiance of over 1000 nmol m'2 s'1. Leaf-to-air vapour pressure difference (VPD) tended to vary in a manner similar to irradiance, remaining close to zero during night, and often reaching values over 3.0 kPa during early afternoon. Maximum VPD in the non-mist system was associated with opening of the propagator lid, which caused an immediate decline in r.h. When the propagator lid was kept closed, VPD under mist was consistently 2-3 times higher than under non-mist. The relationship between VPD and irradiance was found to vary both diurnally and from week to week. In general, a large part of the variation in VPD was unaccounted for by irradiance, as air temperature in both systems increased during the day, producing a higher VPD for a given irradiance later in the day. In addition, the influence of irradiance on the different components of VPD differed between the two systems. Spatial variation in microclimate was of a similar magnitude in both systems. These results highlight the suitability of the non-mist propagation system for use in rural tropical areas. The implications of the results for development of operational guidelines are discussed.

This publication has 0 references indexed in Scilit: